Hitherto, in general, coated tools in which the surfaces of tool bodies made of tungsten carbide (hereinafter, referred to as WC)-based cemented carbide, titanium carbonitride (hereinafter, referred to as TiCN)-based cermet, or a cubic boron nitride (hereinafter, referred to as cBN)-based ultrahigh-pressure sintered body (hereinafter, collectively referred to as a tool body) are covered with a Ti—Al-based complex nitride layer as a hard coating layer through a physical vapor deposition method are known, and it is known that these coated tools exhibit excellent wear resistance.
However, although the coated tool coated with the Ti—Al-based complex nitride layer in the related art has relatively excellent wear resistance, in a case of using the coated tool under high-speed intermittent cutting conditions, abnormal wear such as chipping easily occurs. Therefore, various suggestions for an improvement in the hard coating layer have been made.
For example, JP-A-2000-144376 discloses that a coating which is excellent in wear resistance, seizure resistance, and oxidation resistance, has a low coefficient of friction, and has good sliding characteristics is obtained by forming a complex hard coating made of at least two types of metal nitride among nitrides of Cr, Ti, Al, and V on the surface of a tool body and causing the strength ratio I(111)/I(200) between the strengths I(111) and I(200) of the X-ray diffraction peaks of a (111) plane and a (200) plane obtained through X-ray diffraction of the hard coating to be a value of 3 to 6.
For example, JP-T-2011-516722 describes that by performing chemical vapor deposition in a mixed reaction gas of TiCl4, AlCl3, and NH3 in a temperature range of 650° C. to 900° C., a (Ti1−xAlx)N layer in which the value of the amount x of Al is 0.65 to 0.95 can be deposited. However, this literature is aimed at further coating the (Ti1−xAl2)N layer with an Al2O3 layer and thus improving a heat insulation effect. Therefore, the effects of the formation of the (Ti1−xAlx)N layer in which the value of the amount x of Al is increased to 0.65 to 0.95 on cutting performance is not clear.
In addition, for example, JP-T-2011-513594 suggests that the heat resistance and fatigue strength of a coated tool are improved by coating a TiCN layer and an Al2O3 layer as inner layers with a (Ti1−xAlx)N layer (x is 0.65 to 0.90 in terms of atomic ratio) having a cubic structure or a cubic structure including a hexagonal structure as an outer layer, and applying a compressive stress of 100 MPa to 1100 MPa to the outer layer.